You wouldn’t put your newborn child into dirty blankets for fear of dangerous germs in the bedding, so don’t germinate your garden seed in anything but fresh, soilless seed starting mix. Used or natural soil is riddled with fungal microbes, called Pythium and Phytophthora fungi, which are fatal to seedlings. They quickly cause roots and tender stems to rot.
Under warm, wet conditions ideal for seed germination, these fungi flourish. They’ll attack tender new sprouts as they break ground.
Preventing Seedling Damping Off
Use Clean Bedding to Sow Seeds Indoors.
What prevents damping off from getting a foothold is fresh mix, moderate water, sunlight, and airflow. Black Gold Seedling Mix is light and airy in texture, so it encourages drainage and good aeration, even when it’s warm and wet. Even the most dainty sprout will rise to sunshine without difficulty in this lightweight yet absorbent mix.
Unopened bags of Black Gold Seedling Mix do not contain the fungi that cause damping off. Fresh seedling mix also resists packing down and rarely retains too much moisture. Once you have opened a bag, seal it after use to help keep it free of disease-causing fungi because these spores can be in the air where conditions are damp and plants are growing.
Before sowing into Black Gold Seedling Mix, moisten the mix with warm water. Mix it as you would a salad by turning the material lightly with your hands, over and over until evenly wetted. Like salad, keep it light and just apply light pressure after sowing the seed.
To learn more about indoor seed starting, read the following articles:
Gardeners that start seeds at home have lots of containers to choose from. You can buy seed-starting flat kits, peat pots, reused containers, or even make seedling soil blocks. Some are more costly, while others allow you to grow more for less. My preference is to germinate seed in recycled containers to save your money and reuse plastic waste. Here is what to look for in good containers for seed starting.
Provide Cover
The biggest challenge when germinating seed is keeping the soil evenly moist, but not wet. Good cover with clear or translucent plastic tops ensures surface moisture. This is especially important in dry climates where evaporation rates are
Cheese Tray: This tray and cover saved after an office party makes the perfect enclosure for germinating seeds in small containers.
much higher. These regions are the hardest places to grow anything from seed. (In more humid climates cover is not always required.) If you let pots go dry for just a day or two, tender young sprouts may wither. If you’re busy with the kids or gone at work all day, you won’t be able to rescue wilted seedlings. If they suffer long enough, they will die. In the earlier stages of seed germination and growth, covers provide a safety net.
Seed Starting Containers
One of the most common seed-starting mistakes is sowing seed directly into deeper pots. In some cases, the soil surface can quickly dry out while deeper down it can remain wet, even saturated. When you rewet the surface soil where seeds lie, you risk further saturation deeper down, which can stimulate fungal disease or undesirable saturated soil conditions. Once a seedling’s roots grow downward, this can cause trouble.
For this reason, accomplished gardeners germinate their seed in smaller containers. If you don’t have seedling flats, recycled clear plastic fruit, vegetable, or take-out food containers
Salad Box: Clear-lidded take out boxes make ideal germination chambers.
with tops are ideal. The ability to close the top greatly reduces the rate of surface evaporation, thereby maintaining moist conditions without the need to apply more water. If lids are not available, plastic wrap can do the job. Just make sure there are holes in the top and bottom for oxygen and free drainage.
For larger projects, consider using purchased, lidded nursery flats with cell packs. For smaller plants, choose flats with smaller cells and for larger plants go for larger cells.
The goal of all these choices is to turn containers into miniature greenhouses where seeds are kept warm, stay evenly moist, and will be quick to germinate. Within this environment, control temperature and moisture levels by opening and closing the lid all or part way. (Click here for a vegetable seed-starting temperature chart.) This allows more or less air exchange during periods of wet or dry weather.
Fill the bottom of containers or cell packs with a few inches of pre-moistened, fresh Black Gold Seedling Mix, which is OMRI Listed for organic growing. Into this sow your seed. Once up and growing, each seedling will soon be transplanted into its own growing container.
Six Pack: Keep newly sown seed moist under clear plastic wrap until seeds germinate, then the plastic comes off.
Upgrading Containers
As seedlings grow, they often need more space to reach full planting size. For this second stage use six-packs or four-inch pots and Black Gold Natural & Organic Potting Soil. Larger pots will be needed for larger plants, such as tomatoes or zinnias. The transplanting process is explained in part six of this series (see the link below).
The most important part of starting the garden indoors is your choice of containers. The right one makes this easy to do, but the wrong choice can leave you perpetually struggling to keep moisture and warmth at optimal levels. Yes, it may be easier to get started with an expensive growing seed-starting kit, but you’ll pay for it.
Why not reuse free plastic containers from salad boxes to yogurt cups to help the environment? Or use all those containers you saved from previous season’s nursery-grown bedding plants. Clean them up in some hot water and soap, and they will be good to go. There’s no need to spend your money on anything except quality seed, seedling mix, and organic potting soil to get your garden off to a flying start indoors this year.
The first step of any seed sowing project is to read the entire label of the seed packet. That tells you how deep to plant each kind of seed and under what growing conditions. Those that are usually started indoors may be surface sown or planted 1/2 inch deep, depending on seed size and growing preferences. Each plant’s seeds have there own needs for germination, and some requirements are more complicated than others. Lucky, the seeds of garden vegetables and most annuals are quite easy to grow.
Choose the Right Mix
Whether you sow into cell pack trays or directly into individual containers, make sure you use fresh Black Gold Seedling Mix to provide a good growing environment. It is a soilless mixture, often called media, is comprised of fine Canadian sphagnum peat moss, perlite, and a wetting agent. These ingredients ensure that it’s lightweight and takes up water easily. Set aside a container of dry media, then moisten it before filling your containers. Press it gently into your growing containers, but don’t it pack down, so it remains porous enough to for oxygen and moisture exchange.
The Right Planting Depth
Before planting, created holes at the required depth using a dibble stick or repurposed knitting needle in your cells or pots. If you’re growing in a tray or recycled container score rows in the media to the indicated depth. If you’re growing in 4-inch pots, poke three seed holes spaced apart. Now it’s ready for the pots to receive seed.
There’s no challenge with large seeds because these are easy to sow with your fingers and require a deeper planting depth. The tiny ones can be a bigger challenge to handle. Some gardeners take a piece of scrap paper and fold it in half. Into the V at the bottom, a small number of seeds may be placed; then the paper held folded. Tap the bottom and from the lower end of the fold will come the tiny seeds. They’ll drop precisely into your rows or pots, one at a time. Beware of planting too densely because this makes it tough to untangle the seedlings when the time comes to transplant them. Very tiny seeds should also be sown on the surface. After watering, they will become covered enough with media. (To learn more about seed sowing depths for popular crops, click here.)
Once sown, use any reserved dry media to cover seeds. For deeper planted seed cover them with excavated material from the planting hole or row. Then gently press down the media to ensure good soil contact.
Storing Seeds
When sowing is completed, be sure to seal any remaining seeds inside their packets, and store them in a cool, dry place. If you have an unexpected germination problem, the backup seed will be vital for replanting. Being able to refer back to the instructions in the packet can also come in handy.
Every gardener has done it at least once. Watering newly sown pots too aggressively, which dislodges seeds, moving them all across the soil surface. That’s why watering indoor seedlings properly is essential in the first weeks after sowing.
Watering Seeds
How you water seeds depends on the sowing depth, pot size, and available watering tools. Shallowly planted seeds need more gentle watering tools, such as misters, while more deeply planted seeds can tolerate the water pressure from fine watering cans and spray nozzles. They can also be bottom watered from their tray or dish.
If you live in a warmer climate, take pots or flats outside to water. Buy a nozzle for your hose with a mist setting to gently soak pots. With a misting nozzle, you can water the soil’s top layer without over-saturation. Bottom watering will help moisten the soil below. Where winters are cold, rely on super-fine sprayers or misters.
Fine Spray: This short-handled water wand features a fine spray nozzle ideal for young seedlings.
Watering Seedlings
For seedlings, there are two watering options–top or bottom watering. If you like to water from the top, tiny seedlings should continue to be misted, but once they develop several leaves, they can be watered with a small watering can or nozzle with fine, well-distributed flow. Make sure you water enough to allow the soil to drain to the bottom. Let surface soil become somewhat dry between watering to avoid fungus gnat and fungal disease problems. (Click here to watch our video about fungus gnats.)
Mist: Adjustable nozzles offer a mist setting for seedlings.
Bottom watering pots from trays or saucers allows moisture to wick up through the drain holes to growing roots. It wets the soil mass completely without dry pockets. This bottom-up method may be repeated every week or two, depending on how hot and dry the local climate.
Finally, keep your eye on the weather as the weeks pass. When conditions are humid, water less. When it’s hot or dry, water more often. Overwatering can lead to root and stem rot and underwatering will parch and kill seedlings.
As you bring your seedlings outdoors to harden off, watch out for windy weather as it tends to rapidly draw moisture out of both the foliage and the soil. Then check your crop twice a day to determine watering needs, and let Mother Nature take care of the rest.
Most seedlings will need to be transplanted as they grow. Larger containers and a more robust mix with added fertilizer will enable seedlings to become large, vigorous plants. (Note that good seed starting mix contains no added fertilizer because it keeps some seeds from germinating.). As long as the light is plentiful, repotting will help your seedlings develop stronger roots and shoots.
Seedling Pot Size
A 3- or 4-inch plastic pot or larger cell packs are ideal for the transition. If you want to reuse containers for a greener approach, use recycled tin cans, yogurt cups, or similar-sized containers; punch two to three holes in the bottom of each for drainage. Use a hammer and thick nail for tin, and a paring knife or screw driver to poke holes into plastic (wear protective hand coverings when punching holes). For bottom support recycle flats from the garden center or line your pots up in a baking pan or any low, watertight container.
Seedling Potting Mix and Fertilizer
The potting mix you choose depends on your preference and garden type. If you like planting mix with added fertilizer, choose Black Gold® Moisture Supreme Container Mix or Black Gold All Purpose Potting Mix. Both feed products for up to 6 months. If your plants are going into an organic garden, use OMRI Listed Black Gold Natural & Organic Potting Soil. It is fertile, well-aerated, and holds water well. Because it does not contain a fertilizer boost, apply any quality, water-soluble organic fertilizer.
Fill each pot or container with soil to one-quarter to half-inch below the rim, so there’s enough room for water without overflow.
Transplanting Seedlings
Transplanting your seedlings should be done with a gentle hand. Use an ice cream stick or blunt butter knife to ease seedlings out of the media without tearing roots or disturbing the next seedling in line. Lift it from its roots. Always support the roots with the palm of your hand and lift a seedling by its leaves rather than stems, which are easy to bend or crush. Remove one seedling at a time. Use your finger or a dibble stick to open a hole in the potting soil large enough to accommodate the entire root system comfortably.
Plant: Don’t pick up seedlings by the stem; support the roots with your hand.
When transplanting tomatoes, they can be planted much deeper into the soil so new roots will form on the underground part of the stem. This is a rarity. With most other seedlings, transplant them at the same depth. Hold the seedling by the leaf and gently place the roots in the hole then cover with additional mix and lightly press it down. Next, water your seedlings gently. Allow them a week to revive from transplanting.
Hardening off Seedlings
On mild days take the whole flat of seedlings out onto the porch or covered outdoor area with partial sun to help them become adapted to outdoor wind and light. This transitional period is called “hardening off,” which is essential to toughen tender indoor plants to the harsher growing conditions of the outside. Over a week or two, slowly move them into higher light, if they are full-sun plants. If nights become warm, leave thems outdoors overnight to better adapt. Just keep them out of reach of curious pets and hungry wildlife.
With the nutrient-rich soil, growth will speed up so your seedlings will benefit from lots more direct sunlight. Just be careful over the first few days to ensure they adapt well to the exposure without wilt or burning.
“How early can I start seeds in lower Michigan? Question from William of Southgate, Michigan
Answer: It depends on whether you are growing, annuals, perennials, summer vegetables or spring vegetables. Here’s what I suggest for your USDA Hardiness Zone 6 planting area. (These suggestions may also apply to other gardeners, based on their own specific seasonal planting windows.)
Spring Vegetables: I recommend starting cool-season broccoli, cabbage, cauliflower, kale, lettuce, Swiss chard, and spring onion seeds indoors as early as late January, or a month and a half before the spring soil can be worked. Arugula, beets, cilantro, spring carrots, peas, radishes, and turnips should all be starting in-ground as soon as the soil can be worked. Be sure to amend the soil well with compost, label rows, and cover newly planted seeds with a light layer of compost before watering them in. Keep them just moist and they should sprout as the soil gets warmer.
Summer Vegetables: Warm-season vegetables and herbs, like basil, eggplant, tomatoes, peppers, and tomatillos, should be started indoors as early as the start of February, or three or more months before planting them outdoors. [Click here for an article about growing tomatoes from seed.] Fast-growing cucumbers, melons, pumpkins, and squash can be planted indoors or out. I prefer starting outdoors in well-amended beds after the threat of frost has passed. Beans, corn, okra, and summer beets (click here for a beet-growing video) and carrots can be started by seed outdoors after the threat of frost has passed. (Click here to search for the average frost date in your area.)
Annuals: Wait until February to start flowering annuals and March or April to start vining annuals, which often grow very quickly and can take over your indoor growing area. To learn more, watch the video below for annual seed-starting tips.
“Is it better to grow onions from seeds or from sets in my zone?” Question from Karen of Randolph, Vermont
Answer: Really it depends on how much money you want to spend and how long you want to wait for an onion crop. It is less expensive to grow onions from seed, but you have to start them very early to get a crop, especially when you have a shorter summer. It also depends on the type of onion you are growing. I would recommend growing spring/bunching onions and leeks from seed in your zone, but I would rely on onion sets for robust summer and fall onions.
Northern gardeners like you should also choose day-neutral or long-day onions. Both are sure to reliably produce a good crop up north. Try the day-neutral AAS-winning ‘Sierra Blanca’ or long-day ‘Redwing’ for great results. For bunching onions try the purple buncher, ‘Deep Purple’.
Onions grow best in loose, friable soil, so amend your soil with quality compost, like OMRI Listed Black Gold Garden Compost Blend, before planting. Fertilizing with bone meal will also help your onions along. If starting seeds, check out Black Gold Seedling Mix, which is also approved for organic gardening.
“Is it safe to re-use Black Gold for starting seeds, etc.? Do I need to sterilize it the following year before planting? I had several flats of seeds with low germination or die-off last Spring and would like to use the soil again. Thanks.” Question from Piper of Petersham, Massachusetts
Answer: It is always safer to start with fresh Black Gold Seedling Mix. This will ensure the mix is ready for growing and pest and disease free. Always choose a bag that’s closed at the ends and has no holes, to make sure the mix inside is fresh. the
Old mix can, however, be sterilized for reuse. It will not be as fresh, but the sterilization process will ensure it is pest and disease free. In fact, I sometimes sterilize fresh seedling mix when I am starting prized seeds. To sterilize mix, I place it in a large, oven-safe pan, add some water to moisten the mix, and then cover it with aluminum foil. Then I bake it at 180-200 degrees Fahrenheit for at least 30 minutes. The soil’s internal temperature should be at least 180 degrees F for sterilization. Allow the mix to cool before use.
Black Gold Seedling Mix is high performing and OMRI Listed, meaning it’s approved for organic gardening. It is formulated for seed starting, cuttings, and seedling production. You’ll love its rich mix of Canadian Sphagnum Peat Moss, Organic Wetting Agent, Perlite, and RESiLIENCE®. Give your seedlings a boost this season with Black Gold Seedling Mix!
Ever wanted to learn how to grow your own annual garden flowers and bedding plants from seed? This easy how-to shows simple steps to successfully growing your own garden flowers. It’s easy and saves money. This how-to shows how to grow your own flower seeds from start to finish.
